1. Field of the Invention
The present invention relates to an optical module mounted body and a method of securing an optical module to a mounting board.
2. Related Art
Optical modules having an optical semiconductor element such as a semiconductor laser diode (hereinafter referred to as LD) are generally mounted on a mounting board formed with a predetermined wiring patterns.
FIG. 1-16 shows an example of the optical module mounted on a mounting board, which is disclosed in U.S. Pat. No. 6,522,486.
In this prior art, the optical module is placed directly on a mounting board. A securing member is placed over a package of the optical module and fastened to the mounting board by use of screws on the bottom end flanges of the securing member. The optical module is held between the securing member and the mounting board, thereby fixedly pressed against the mounting board. The heat generated by an LD inside the optical module is dissipated through a bottom face of the package to the mounting board and ultimately into the air.
In this securing method of the optical module, however, if a turning torque of the screws is not sufficient, the optical module and the mounting board are not in properly close contact with each other, while if the torque is excessive, the mounting board or the securing member may be deformed or damaged, leading also to an improper contact. Thus, a reduced heat transferring efficiency between the optical module and the mounting board results in both cases.
It is for this reason that the prior art requires a turning torque of the screws to be strictly controlled.
In addition, the prior art securing method requires flanges at which the securing member is fastened to the mounting board. Those flanges project beyond the main body and inevitably occupy some space on the mounting board. However, the package should be free of such flanges in pursuing downsizing of the optical module and of the mounting board mounted with the optical module.
Further, in adopting an easy method of securing the optical module to a mounting board, a care should be paid to ensure or to enhance the heat dissipation from the LD to the mounting board.